Smell is the faculty or power of perceiving an odor or scent of something In humans, smells are perceived when odorant molecules bind to specific sites on olfactory receptors—membrane proteins contained in specialized sensory cells of the nasal cavity used to detect the presence of smell. In comparison to other animals, humans have a lesser proportion of these cells relative to certain respiratory cells, resulting in a less keen sense of smell than many animals. This less keen sense of smell inhibits many people from recognizing whether food is spoiled, determining what ingredients are in food, deciphering smells from certain beverages, and so on. Of more serious consequence though, humans' less keen sense of smell can inhibit them from recognizing dangerous conditions, such as gas leaks, the presence of carbon monoxide, the presence of predatory animals, and so on.
Due at least in part to this deficiency in detecting smells, efforts have been made to develop technologies capable of detecting smells. One such example is gas sensing technology, which is utilized for gas detection. Gas sensing technology has been limited in its performance, however, because it suffers from a variety of drawbacks such as poor ability to discriminate between gases (e.g., volatile organic compounds), sensitivity to humidity, high power consumption (e.g., can involve a 500 degree Fahrenheit temperature to operate), and so on. Conventional smell detecting techniques are also limited to pattern recognition on an array of weak chemical bonds. The drawbacks of conventional smell detecting devices and techniques render them unsuitable for widespread use in consumer and medical applications.